Investigation of seasonal and diurnal cycles on the height dependence of optical turbulence in the lower atmospheric boundary layer

Analysis of wave propagation in the visible and near infrared (IR) has to take into account the influence of optical turbulence due to variations of temperature. Especially the operation area of most electro-optical systems in the lower atmospheric boundary layer is affected by atmospheric turbulence. The influence of thermal and mechanical turbulence on the height dependency of the structure function parameter of the refractive index Cn² is investigated. Cn² is used for the characterization of optical turbulence. The main focus is set on seasonal and diurnal variations. The variations dependent on atmospheric stability in the surface layer and the nocturnal residual layer are analysed. Results are presented from the long-term experiment VerTurm (Vertical Turbulence Measurements). The experiment is continuously performed since June 2009 in rural country at north-western Germany. The vertical structure of optical turbulence is explored using three different measurement techniques to cover the altitude range between the surface and about 250 m height. Model comparisons are carried out and discussed.

[1]  R. Stull.  An Introduction to Boundary Layer Meteorology , 1988 .

[2]  R. A. Silverman,et al.  Wave Propagation in a Turbulent Medium , 1961 .

[3]  Edgar L. Andreas,et al.  Estimating Cn 2 over snow and sea ice from meteorological data , 1988 .

[4]  Detlev Sprung,et al.  Stability and height dependant variations of the structure function parameters in the lower atmospheric boundary layer investigated from measurements of the long-term experiment VERTURM (vertical turbulence measurements) , 2011, Remote Sensing.

[5]  R. S. Lawrence,et al.  Refractive-index and absorption fluctuations in the infrared caused by temperature, humidity, and pressure fluctuations , 1980 .

[6]  Karin R. Weiss-Wrana.  Turbulence statistics in littoral area , 2006, SPIE Remote Sensing.

[7]  V. I. Tatarskii.  The effects of the turbulent atmosphere on wave propagation , 1971 .

[8]  Thomas Foken,et al.  Angewandte Meteorologie : mikrometeorologische Methoden , 2003 .

[9]  Frans T. M. Nieuwstadt,et al.  Temperature measurement with a sonic anemometer and its application to heat and moisture fluxes , 1983 .

[10]  Karin R. Weiss-Wrana.  Turbulence statistics applied to calculate expected turbulence-induced scintillation effects on electro-optical systems in different climatic regions , 2005, SPIE Optics + Photonics.

[11]  Gordon E. Schacher,et al.  Measurements of the humidity structure function parameters, Cq2and CTq, over the ocean , 1980 .

[12]  Statistical analysis of measurements of atmospheric turbulence in different climates , 2002, SPIE Remote Sensing.

[13]  Frederick G. Smith,et al.  The Infrared & Electro-Optical Systems Handbook. Atmospheric Propagation of Radiation, Volume 2. , 1993 .